package demo3;

public class Computer {
    public void powerOn() {
        System.out.println("打开电脑");
    }

    public void powerOff() {
        System.out.println("关闭电脑");
    }

    public void usbDevice(USB usb) {
        usb.openDevice();
        if (usb instanceof Mouse) {
            Mouse mouse = (Mouse) usb;//向下转型
            mouse.click();
        }else if(usb instanceof keyBoard){
            keyBoard keyboard = (keyBoard) usb;
            keyboard.inPut();
        }
        usb.closeDevice();
    }
}
